CVE-2022-48921

Medium

In the Linux kernel, the following vulnerability has been resolved: sched/fair: Fix fault in reweight_entity Syzbot found a GPF in reweight_entity. This has been bisected to commit 4ef0c5c6b5ba ("kernel/sched: Fix sched_fork() access an invalid sched_task_group") There is a race between sched_post_fork() and setpriority(PRIO_PGRP) within a thread group that causes a null-ptr-deref in reweight_entity() in CFS. The scenario is that the main process spawns number of new threads, which then call setpriority(PRIO_PGRP, 0, -20), wait, and exit. For each of the new threads the copy_process() gets invoked, which adds the new task_struct and calls sched_post_fork() for it. In the above scenario there is a possibility that setpriority(PRIO_PGRP) and set_one_prio() will be called for a thread in the group that is just being created by copy_process(), and for which the sched_post_fork() has not been executed yet. This will trigger a null pointer dereference in reweight_entity(), as it will try to access the run queue pointer, which hasn't been set. Before the mentioned change the cfs_rq pointer for the task has been set in sched_fork(), which is called much earlier in copy_process(), before the new task is added to the thread_group. Now it is done in the sched_post_fork(), which is called after that. To fix the issue the remove the update_load param from the update_load param() function and call reweight_task() only if the task flag doesn't have the TASK_NEW flag set.

Package Linux Kernel
Published 2024-08-22
Last modified 2024-09-12
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

4.7

out of 10
Medium
Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High
Vector string
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness type

CWE-362

CVE-2022-48921 is a Race Condition vulnerability

What is Race Condition?

The product contains a code sequence that can run concurrently with other code, creating unexpected states. Learn more on MITRE CWE

Affected versions

Linux kernel versions 5.10.80, 5.15.3, 5.14.19, 5.16 and later are affected. Fixed in 5.10.137, 5.15.27, 5.16.13, 5.17 and their respective stable series.

Affected from
≥ 5.10.80 ≥ 5.15.3 ≥ 5.14.19 ≥ 5.16
Fixed in
✓ 5.10.137 5.10.x ✓ 5.15.27 5.15.x ✓ 5.16.13 5.16.x ✓ 5.17

References

The following references provide additional information about CVE-2022-48921 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

4 patch commits total View all on NVD

Frequently asked questions

  • What is CVE-2022-48921?

    CVE-2022-48921 is a Medium severity Linux kernel vulnerability with a CVSS score of 4.7 out of 10 , classified as a Race Condition flaw (CWE-362) . It affects Linux kernel versions from 5.10.80 onward and has been patched in 5.10.137, 5.15.27, 5.16.13 and others. CVE-2022-48921 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2022-48921?

    CVE-2022-48921 has a CVSS score of 4.7 out of 10, rated Medium severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H .

  • Is there a patch available for CVE-2022-48921?

    Yes — CVE-2022-48921 has been patched. Fixed versions include 5.10.137, 5.15.27, 5.16.13 and others. If you are running Linux kernel 5.10.80 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2022-48921 actively exploited?

    No — CVE-2022-48921 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

  • What is Race Condition (CWE-362)?

    The product contains a code sequence that can run concurrently with other code, creating unexpected states. View CWE-362 on MITRE CWE →

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